From patchwork Mon Feb 10 19:37:50 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13968884 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2606BC021A1 for ; Mon, 10 Feb 2025 19:38:41 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 93F8810E601; Mon, 10 Feb 2025 19:38:40 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.b="PdE02XrA"; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id C74A310E600 for ; Mon, 10 Feb 2025 19:38:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739216318; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8sC+CKPivo9nJ2nwAVN+E4SAgEKJPEiCVQrD/mzwcqM=; b=PdE02XrAQ0Z3/Ks7U0EExqc5jHg+iXq8xaygP2zD56pBR0wV0Xp9iIJZLOARoAfeLZDwTi h8Za3ZPWLahslaLCX/0DTXTI+vBvT1koONkJyptkdL10130Sp+aoYjPXHh90X4coRYib3u +Nj62xbcvj14Jd8gYNiHMowR1L6wwAA= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-297-7QNDySFTMrm0_IRTxrImBQ-1; Mon, 10 Feb 2025 14:38:36 -0500 X-MC-Unique: 7QNDySFTMrm0_IRTxrImBQ-1 X-Mimecast-MFC-AGG-ID: 7QNDySFTMrm0_IRTxrImBQ Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-4392fc6bceaso13133405e9.2 for ; Mon, 10 Feb 2025 11:38:36 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1739216315; x=1739821115; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=8sC+CKPivo9nJ2nwAVN+E4SAgEKJPEiCVQrD/mzwcqM=; b=JCAHHKsbwLfH5I6Dj6Nl66moFBen5fZ2kbnbHxfojtYNezc/So19KsZ88VK/p6oev5 P9YNlUv1eukPRFAjg1wjuzTNoSV9gyq8qGrRdndyY4m2DB17RtwavqD7FQAeC07+nDgR cT13SfY3X7yl7HPDFUnQvUeP3GHqQgsjvdYLJl/wJ2nDwRkn2yIq/cbtUgAMy6Ce2I3j gUL1Lxpl6A7YUlsWonDpDqmPrPGFooYJQOYWXGDql6phAIFg3al7Ni/S/gfEZbqBlem/ DCdi1a2clbEAa8r7IBexG3TATFAJiBFMoTwIaHlmmZaE38rYhJgcLu35N/WyBJdtm+EG kesg== X-Forwarded-Encrypted: i=1; AJvYcCUjgEGaVAkUmpwqst/5s0mNReSdLthzPm5wT3uN5qN9qwjt6EXtaD6oGwUBNmTL7lQHSaHqVFfcehw=@lists.freedesktop.org X-Gm-Message-State: AOJu0YxQLqeGwEYxEIIqSEkEfoGJc5F2wMydXrohpDQ2PJpLcmVXs7Hz tdhKcD5RomMVAH5PjsRIqyG/k3CWP41wcyBifPLmGTOs7zXvPiumnXAZmhBc+z67h5N8J5vGCax WgpDo/W+HCwaSrNGT9Z9euo0+7PhG+PgTH1lJA91ZFK8Jp47+Tto3CYsttfRCe8M+kw== X-Gm-Gg: ASbGnctzmvM0wIRmdIHScLE6IG8uwHC1/3p1RuQMwAVbV83chPwWjFRsbNofV7V/u2d RVozPvSoRJq0ovWv8kW84fUu3SnHPYNmUKQEsQ3gHqeKYvUD9ymkKhJY5aTk6xzArZcWDqNSIAg hU5mRLCrWikHb1G3MfZtsDSe2pbMSdgWY+OkLF9MmUgJ4kO+i4xxtPcSl6ieLkh8YNKXdXyWckC T9X+lg2c/R6SkT3vbyPIAmvfFkS0dnKigJdnAzrmGBhFHdb2h1aiyPdbPZ3zUiJMrPBRRE0LPiD 590SKX/6w06TFXXQFemgwlCEcYRlOKkrxe3mqDqqdfkgy2V2t1WZiw3fzyLl97dSjg== X-Received: by 2002:a05:600c:4e91:b0:439:4637:9d9 with SMTP id 5b1f17b1804b1-43946370d97mr43287365e9.12.1739216315597; Mon, 10 Feb 2025 11:38:35 -0800 (PST) X-Google-Smtp-Source: AGHT+IF6B7q2dhfsb9dj8LY+8M1CJU6DFUQTZK7m2VERaPDmly8AB+qIiZRItOcPeyw5uy4LKosd2g== X-Received: by 2002:a05:600c:4e91:b0:439:4637:9d9 with SMTP id 5b1f17b1804b1-43946370d97mr43287075e9.12.1739216315147; Mon, 10 Feb 2025 11:38:35 -0800 (PST) Received: from localhost (p200300cbc734b80012c465cd348aaee6.dip0.t-ipconnect.de. [2003:cb:c734:b800:12c4:65cd:348a:aee6]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-4390d94d802sm195260345e9.12.2025.02.10.11.38.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 Feb 2025 11:38:33 -0800 (PST) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-doc@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, nouveau@lists.freedesktop.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, damon@lists.linux.dev, David Hildenbrand , Andrew Morton , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Jonathan Corbet , Alex Shi , Yanteng Si , Karol Herbst , Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , SeongJae Park , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Pasha Tatashin , Peter Xu , Alistair Popple , Jason Gunthorpe Subject: [PATCH v2 08/17] kernel/events/uprobes: handle device-exclusive entries correctly in __replace_page() Date: Mon, 10 Feb 2025 20:37:50 +0100 Message-ID: <20250210193801.781278-9-david@redhat.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250210193801.781278-1-david@redhat.com> References: <20250210193801.781278-1-david@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: l6MJgVZ5YrciFj3P0DJGxWEW2hZiV0MBN2He78kiXnA_1739216316 X-Mimecast-Originator: redhat.com content-type: text/plain; charset="US-ASCII"; x-default=true X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Ever since commit b756a3b5e7ea ("mm: device exclusive memory access") we can return with a device-exclusive entry from page_vma_mapped_walk(). __replace_page() is not prepared for that, so teach it about these PFN swap PTEs. Note that device-private entries are so far not applicable on that path, because GUP would never have returned such folios (conversion to device-private happens by page migration, not in-place conversion of the PTE). There is a race between GUP and us locking the folio to look it up using page_vma_mapped_walk(), so this is likely a fix (unless something else could prevent that race, but it doesn't look like). pte_pfn() on something that is not a present pte could give use garbage, and we'd wrongly mess up the mapcount because it was already adjusted by calling folio_remove_rmap_pte() when making the entry device-exclusive. Fixes: b756a3b5e7ea ("mm: device exclusive memory access") Signed-off-by: David Hildenbrand --- kernel/events/uprobes.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 2ca797cbe465f..cd6105b100325 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -173,6 +173,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, DEFINE_FOLIO_VMA_WALK(pvmw, old_folio, vma, addr, 0); int err; struct mmu_notifier_range range; + pte_t pte; mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, addr, addr + PAGE_SIZE); @@ -192,6 +193,16 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, if (!page_vma_mapped_walk(&pvmw)) goto unlock; VM_BUG_ON_PAGE(addr != pvmw.address, old_page); + pte = ptep_get(pvmw.pte); + + /* + * Handle PFN swap PTES, such as device-exclusive ones, that actually + * map pages: simply trigger GUP again to fix it up. + */ + if (unlikely(!pte_present(pte))) { + page_vma_mapped_walk_done(&pvmw); + goto unlock; + } if (new_page) { folio_get(new_folio); @@ -206,7 +217,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, inc_mm_counter(mm, MM_ANONPAGES); } - flush_cache_page(vma, addr, pte_pfn(ptep_get(pvmw.pte))); + flush_cache_page(vma, addr, pte_pfn(pte)); ptep_clear_flush(vma, addr, pvmw.pte); if (new_page) set_pte_at(mm, addr, pvmw.pte,